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I'm building out a FreeNAS based server in a Supermicro X6DHE-XB 3U enclosure with 4G of RAM, 16 SATA hot-swap bays. It comes with 2x8 port 3Ware RAID cards, but I'm planning on just using the ZFS capabilities instead of the hardware RAID. My initial drive set will be 8x2TB HITACHI Deskstar 7K3000 HDS723020BLA642 drives.

If I was using hardware based RAID, it would give me a red light on the drive bay where the drive failed. How does it work with ZFS when a drive fails? I don't think there is any guarantee that sda=bay1, sdb=bay2, etc, so how do you determine which drive needs to be replaced? Can ZFS report back to the SATA controller to turn on the "failed drive" light? Does it just report the drive serial number? What if the drive fails so hard it can't report it's serial number? I suppose it is a good idea to write down every drive's serial number and which bay it went into before you go live. Are there any other "pre-production" tasks to make replacing drives easier in the future?

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2 Answers 2

up vote 3 down vote accepted

zpool status -v should tell you which disk is online or not.

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+1 FreeNAS is FreeBSD based, and the drives will be in the order the card provides. If there is a single 8 port SAS controller, the drives will be /dev/da0 through /dev/da7, with the same numbering as the card (good cables are also labeled per drive). If you have multiple controllers, or anything complicated you can run camcontrol devlist to get a listing of all SAS/SCSI drives and what card, target, lun they are on. –  Chris S Apr 20 '11 at 17:29

I don't believe you can do this with FreeNAS. You might consider NexentaStor Community Edition if you have less than 18TB of data, NexentaStor will identify bad drives for you.

Otherwise you may be stuck with hardware raid.

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